VECURONIUM DOSE REQUIREMENT AND PUPILLARY RESPONSE IN A PATIENT WITH OLIVOPONTOCEREBELLAR ATROPHY (OPCA)

Purpose: Olivopontocerebellar atrophy (OPCA), a variant oi spinocerebe llar degeneration (Shy-Drager syndrome), is a systemic degenerative di sorder affecting the neurons of multiple nuclei. We investigated the s ensitivity to vecuronium and the pupillary responses to various stress es in a patient with OPCA. Clinical features: A 65-yr-old woman with a six-month history of OPCA underwent a left upper lobectomy for lung c ancer under propofol-N2O anaesthesia. She had symptoms of dysarthria, bulbar palsy, cerebellar ataxia, Parkinsonism, myosis, pyramidal signs and muscular atrophy of the distal extremities, A cumulative dose-res ponse curve for vecuronium was constructed, and pupillary changes in r esponse to various noxious stimuli were evaluated with concomitant rec ording of the Spectral-Edge-Frequency 90% (SEF90; the frequency below which 90 percent of the EEG power is located), The dose-response curve for vecuronium and the estimated ED,, value (the 50% blocking dose of vecuronium) in this patient with OPCA were almost identical with thos e of five ASA I-ii patients (27 mu g.kg(-1) vs 31 mu g.kg(-1)). The pu pil size and the SEF90 did not change after tracheal intubation or sur gical stimulation in this patient. while in the control subjects (n = 3), these measures increased in response to both stresses. Conclusions : The absence of pupillary and SEF90 responses to noxious stimuli sugg ests a sensitivity to propofol and/or central autonomic dysfunction in patients with OPCA, Although the dose requirement oi vecuronium in th is patient was similar to that of the control patients, the effects of neuromuscular blockers may vary depending on the severity of muscle a trophy.